Yokel wrote:
"Duncan Heenan" wrote in message
...
| In a discussion of tides recently it was asserted that the spring tides
| occurring at the full moon always had a bigger range than those at the new
| moon. I don't know the answer, but I expect some guru on URS
| will............. I await!
|

In general, the tides at new and full moon are not equal, but sometimes it
is range at new moon which is larger, sometimes that at full.

I cannot remember seeing a full explanation, but the main cause is most
likely to be the eccentricity of the moon's orbit. The moon's distance from
us varies significantly through the month and this would result in a
variation of the gravitational force which produces the tides.

There also is a suntide , and you have to add both,
that gives you all sorts of levels, because they are
not in sync(sun 1 day, moon 1/28th different).
Suntide is moontide, so the summ is mainly locked
to the moon.
I do not think that the shape of the moon orbit
has much influence.